Solved
Sims 4 update March 15th broke my game.
So, since the update of march 15th, the game (Sims 4) is now completely impossible to play for me. I can't change anything to a house in build/buy mode anymore, I can't save and exit the game and if ...
Move your Mods folder to the Desktop and delete localthumbcache.package. Then test the game in a new save.
If it works now check for updates to your Mods and CC. Add it back a little at a time while testing until you have found all that are broken.
